Dynamo-electric machine



Patented July l9, I898.

A. G. EIGNER. DYNAMO ELECTRIC MACHINE.

(Application filed May 7, 1898.)

2 Sheets-Sheet I.

(No Model.)

Patented July 19, I898.

UNITED STATES PATENT OEEIcE.

.ADOLF GEORG EIGNER, OF ST. PETERSBURG, RUSSIA, ASSIGNOR TO THE SIEMENS & IIALSKE ELECTRIC COMPANY OF AMERICA, OF CHICAGO,

ILLINOIS.

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 607,787, dated July 19, 1898.

Application filed May 7,1898, Serial N0. 679,994:- (NO model.)

To aZZ whom it may concern.-

Be it known that I, ADOLF GEORG EIGNER, a subject of the Emperor of Russia, residing at St. Petersburg, Russia, have invented a certain new and useful Improvement in Dynamo-Electric Machines, (Case N0. M8,) of which the following is a full, clear, concise, and exact description.

My invention relates to dynamo-electric machines, and more particularly to an improved construction of the field-magnets for such machines.

In order to prevent cross-magnetization or reversal of polarity of the field-magnet poles by the inductive effect of the armature-windings, there are two methods of constructing the field-magnet. The first is to leave a comparatively large air-gap between the surface of the magnet-pole and the surface of the armature, this air-gap serving to increase the resistance of the magnetic circuit traversed by the lines of force set up by the armaturewindings. This of course correspondingly increases the resistance of the magnetic circuit traversed by the lines of force set up by the field-windings, so that in order to maintain the required density of the field more current must be supplied to the field-windings, the efficiency of the machine thereby being decreased. The other expedient, and the more successful one, is to provide slots in the polepieces of the field-magnet, the slots running in such a direction as to increase the resistance of the external magnetic circuit which must be traversed by the lines of force produced by the armature-windings, while the resistance of the magnetic circuit traversed by the lines of force produced by the field-windings is practically unchanged.

Although it is a well-known fact that the construction of the pole-pieces just described is advantageous and will increase the efficiency of the machine, comparatively few machines are so built. The principal reason for this is that heretofore such construction required casting the field-magnet in several small pieces, bolting the same together, and magnetically separating them from one another.

In accordance with the present invention the field-magnet having any required number of poles is cast in two complemental parts, which may be bolted together and magnetically separated from one another. These two parts or members are so formed that when joined each pole-piece will be formed half of one part and half of the other part, and a slot will be provided in each pole-piece, producedby the distance between its members. Each half of the pole-piece will have a distinct magnetic circuit which is magnetically separated from the magnetic circuit of the other half of the pole-piece, and the slot, extending radially from the armature-shaft,will materially decrease the cross-magnetizing effeet of the armature-windings in a manner well known.

My invention will be more easily understood upon an inspection of the accompanying draw ings, in which- Figure l is an elevation of a dynamo-electric machine having its field-magnet constructed in accordance with my invention. Fig. 2 is a sectional plan view thereof on line 2 2 of Fig. 1. Fig. 3 is a vertical section on line 3 3 of Fig. 2. Fig. at is a detail sectional view on line i i of Fig. 3. Fig. 5 is a diagram illustrating the field-magnet developed into a plane to afford an easier understanding of the details of its construction.

Similar letters of reference are used to designate the same parts wherever they are shown.

The machine illustrated in the drawings is of the multipolar type, having a field-magnet a, provided with four polar projections b e (Z c. The field-magnet a is formed of two members a (0 ,1311?) member a being provided with projections Z) c d e, forming the halves of the poles l) c d 6, respectively. The member a is likewise provided with projections b e (Z c forming the other halves of said poles b c d 6, respectively. The two members a and a are secured together by bronze bolts f f, bronze washers f f being interposed between the two members, so that they are magnetically separated from one another. W'hen the two members are placed together, it will be seen that spaces b c d e are left between the halves of the pole-pieces b 0 cl 6, respectively, these spaces serving to interrupt the magnetic circuit, which will be traversed by the crossmagnetiziug lines of force set up by the armature-windings. Each pole-piece, however, is constructed so as to afford a path of low resistance for the lines of force set up by the field-windings g hi it, disposed about said poles. Two distinct magnetic circuits are thus provided in the field-magnet, one path through the member a, which carries the proj ections b c d e, and the other path, magnetically separate and distinct from the first, through the member a which carries the projections b c d 0 It will be appreciated that the construction above described is quite simple and produces a field-magnetwhose advantages are apparent.

I do not wish to be understood as limiting myself to the precise construction shown in the drawings, for it is evident that various modifications may be made by those skilled in the art without departing from the spirit of my invention; but,

Having thus described one embodiment thereof, I claim as new, and desire to secure by Letters Patent, the following:

1. A field-magnet for dynamo-electric machines, said field-magnet being formed of separate complemental members joined together, each of said members having projections cooperating with the projections of another member to form complete polar projections,

said members being separated to form slots in said polar projections, substantially-as described.

2. A multipolar field-magnet for dynamoelectric machines, said magnet being formed of two complemental members adapted to be joined together and magnetically separated from one another, each of said members having projections adapted to cooperate with the complemental projections of the other member thereby to produce complete polar projections, the magnetic circuit of each of the polar projections thus lying partly in one member and partly in the other, substantially as described.

3. A field-magnet for dynamo-electric machines, said field-magnet being formed of separate complemental members joined together, each of said members having projections adapted to cooperate with similar projections on another member to form complete polar projections, said complemental members bein g magnetically separated from one another, substantially as described.

In witness whereof I have hereunto set my hand in presence of two witnesses.

ADOLF GEORG EIGNER.

lVitnesses:

N. TSCHENALOFF, A. SHKLAREVICH. 

